Create design-hashset.py

Author: kamyu104

Python/design-hashset.py

@@ -0,0 +1,115 @@
+# Time:  O(1)
+# Space: O(n)
+
+# Design a HashSet without using any built-in hash table libraries.
+#
+# To be specific, your design should include these two functions:
+#
+# add(value): Insert a value into the HashSet. 
+# contains(value) : Return whether the value exists in the HashSet or not.
+# remove(value): Remove a value in the HashSet. If the value does not exist in the HashSet, do nothing.
+#
+# Example:
+#
+# MyHashSet hashSet = new MyHashSet();
+# hashSet.add(1);         
+# hashSet.add(2);         
+# hashSet.contains(1);    // returns true
+# hashSet.contains(3);    // returns false (not found)
+# hashSet.add(2);          
+# hashSet.contains(2);    // returns true
+# hashSet.remove(2);          
+# hashSet.contains(2);    // returns false (already removed)
+#
+# Note:
+# - All values will be in the range of [1, 1000000].
+# - The number of operations will be in the range of [1, 10000].
+# - Please do not use the built-in HashSet library.
+
+
+class ListNode(object):
+    def __init__(self, key, val):
+        self.val = val
+        self.key = key
+        self.next = None
+        self.prev = None
+
+
+class LinkedList(object):
+    def __init__(self):
+        self.head = None
+        self.tail = None
+
+    def insert(self, node):
+        node.next, node.prev = None, None  # avoid dirty node
+        if self.head is None:
+            self.head = node
+        else:
+            self.tail.next = node
+            node.prev = self.tail
+        self.tail = node
+
+    def delete(self, node):
+        if node.prev:
+            node.prev.next = node.next
+        else:
+            self.head = node.next
+        if node.next:
+            node.next.prev = node.prev
+        else:
+            self.tail = node.prev
+        node.next, node.prev = None, None  # make node clean
+
+    def find(self, key):
+        curr = self.head
+        while curr:
+            if curr.key == key:
+                break
+            curr = curr.next
+        return curr
+
+
+class MyHashSet(object):
+
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.__data = [LinkedList() for _ in xrange(10000)]
+
+    def add(self, key):
+        """
+        :type key: int
+        :rtype: void
+        """
+        l = self.__data[key % len(self.__data)]
+        node = l.find(key)
+        if not node:
+            l.insert(ListNode(key, 0))
+
+    def remove(self, key):
+        """
+        :type key: int
+        :rtype: void
+        """
+        l = self.__data[key % len(self.__data)]
+        node = l.find(key)
+        if node:
+            l.delete(node)
+
+    def contains(self, key):
+        """
+        Returns true if this set did not already contain the specified element
+        :type key: int
+        :rtype: bool
+        """
+        l = self.__data[key % len(self.__data)]
+        node = l.find(key)
+        return node is not None
+
+
+# Your MyHashSet object will be instantiated and called as such:
+# obj = MyHashSet()
+# obj.add(key)
+# obj.remove(key)
+# param_3 = obj.contains(key)